Narrated by al-Zubayr ibn al-ʿAwwām (رضي الله عنه), the Prophet (صلى الله عليه وسلم) said: “Change the colour of your white hairs, and do not resemble the Jews.” Narrated by al-Tirmidhī: 1752 and graded authentic by Shaykh al-Albānī in al-Sirāj al-Munīr: 5434.
Narrated by Jābir (رضي الله عنه) that the Prophet (صلى الله عليه وسلم) said, upon seeing the whiteness of the hair of Abū Quḥāfah [Abū Bakr’s (رضي الله عنه) father], he said to Abū Bakr: “Take him to some of his woman and let them change it [the white] with something—but refrain from black.” Narrated by Abū Dāwūd: 4204 and graded authentic by Shaykh al-Albānī in Ghāyah al-Marām: 105.
Shaykh al-Islām Ibn Taymiyyah comments:
This wording is evidence that proves that we are commanded to behave contrary to them (the Jews), and that resembling them is forbidden. For, indeed, if he (صلى الله عليه وسلم) forbade resembling them in leaving the whiteness of our hair, which is not from among our intentional acts, then intentionally setting out to resemble them is even more befitting of being forbidden. For this reason, resemblance to them in this way is ḥarām.
Source: Iqtiḍāʿ 1:180-181
Translated by: Riyāḍ al-Kanadī